Field
The present disclosure relates to a light emitting device which uses a light emitting element and a method of manufacturing the light emitting device.
Description of Related Art
Generally, a light emitting device having a light emitting element such as an LED has been required to improve the light extracting efficiency of white light. There has been known a light emitting device to obtain the above, which includes a configuration for increasing the light extracting efficiency of white light at the light extracting surface side of the light emitting element. For example, a semiconductor light emitting element illustrated in JP 2012-119481A has a nitride substrate and a semiconductor layer portion formed on a main surface of the nitride substrate. In the semiconductor light emitting element, the nitride substrate has an inclined exposed surface or an inclined exposed portion.
In the semiconductor light emitting element, the semiconductor layer portion has a quantum well structure active layer which includes a quantum well layer and a barrier layer. In the case where the quantum well layer, the barrier layer, and a second conductive-type semiconductor layer have an appropriate difference in the refractive index, and also the light emitting layer has an appropriate thickness, the semiconductor light emitting element has an anisotropic internal light emitting profile due to isotropic dipole emission. That is, according to JP 2012-119481A, in order to efficiently extract light which is emitted from the active layer structure of the semiconductor layer portion into the semiconductor light emitting element, it is advantageous to have a configuration in which an inclined exposed surface or an inclined exposed portion is provided on the nitride substrate to improve the light extraction efficiency of a high density light traveling in the vicinity of θem max direction (a direction indicates a maximum internal light emission intensity density in the target semiconductor light emitting element at the time of measurement of the light distributing properties.
Further, light travelling in the vicinity of θem max direction has a high density, so that mainly controlling the directions of this portion of light outside of the light emitting element is extremely important, which can be achieved by providing the nitride substrate with an inclined exposed surface or an inclined exposed portion (see JP 2012-119481A). Thus, according to JP 2012-119481A, while appropriately controlling the light distributing properties of a semiconductor light emitting element which can be formed on a nitride substrate, the light extraction efficiency can be also improved.
However, in such a semiconductor light emitting element, further consideration has been needed on the light reflected from an interface between a semiconductor layer portion and a nitride-based substrate and from the light extracting surface, and further, a portion of light reflected inward at the light extracting surface may be eliminated without being extracted from the light extracting surface.